Camera crane arm

ABSTRACT

A camera crane arm has a frame pivotally supporting a central beam section. Outer beam sections are attached to and spaced apart from the central beam section. A leveling system is externally attached to the frame and pivotally linked to a camera platform, to maintain the platform in a level orientation, as the crane arm is pivoted up and down, to adjust camera lens height. The crane arm is formed of sections having vertically offset ends, to reduce sagging. The sections have a high moment of inertia but low weight, and can be assembled without force.

This is a divisional of Ser. No. 08/514,832, filed Aug. 14, 1995, nowU.S. Pat. No. 5,781,814.

BACKGROUND OF THE INVENTION

Camera cranes are often used in the motion picture and televisionindustries to position and maneuver cameras. Camera cranes typicallyhave a crane arm supported on a base, with a camera platform at one endof the arm, and a counterweight at the other end. The crane arm can bepivoted by hand to raise and lower the camera, and also to pan to theleft or right side. A leveling system is often included to maintain thecamera platform in a level orientation.

With the advent of remote controlled television and motion picturecameras, filming can be achieved without a camera operator sittingbehind the camera. Rather, the camera operator can remain on the groundwhile the remotely controlled camera is suspended on a crane arm. Thisallows for more versatile camera positioning. For example, the remotelycontrolled camera can be positioned at locations where it would be tootime consuming, difficult or dangerous to place a traditional camera andoperator. Accordingly, there is a need for camera crane arms to matchthe versatility of remote camera systems.

Due to the variety, and occasionally difficult accessibility of filminglocations, the camera crane arm should advantageously be portable andlightweight. On the other hand, the arm must be rigid enough, whenassembled, to resist bending and sagging, and to avoid excessivewhipping motion on the camera during movement. While various cameracrane arms have been used successfully in the past, there remains a needfor an improved camera crane arm to meet the needs of the television andmotion picture industries.

SUMMARY OF THE INVENTION

To these ends, a camera crane arm preferably includes a frame pivotallysupporting a central box section. A plurality of outer beams areattached to and spaced apart from the central box section. A levelingsystem is advantageously fixed to the box section in between outerbeams, and pivotally linked to a camera platform, to maintain theplatform in a level orientation.

Advantageously, the crane arm is most desirably formed of sectionshaving substantially flat ends, with a first end having one or moretapered pin and the second end having a like number of mating taperedholes, with the pins and holes of adjacent sections configured to engageeach other when the flat ends of adjacent sections are brought together,thereby forming a secure and rigid attachment between sections.Preferably, the beam sections have a built-in vertical offset betweenthe first and second ends, to reduce sagging of the arm.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein similar reference characters denote similarelements throughout the several views:

FIG. 1 is a side elevation view of a preferred embodiment of the presentcamera crane arm;

FIG. 2 is an enlarged side elevation view showing the frame section ofthe crane arm of FIG. 1;

FIG. 3 is a top and left side isometric view of a preferred crane armsection;

FIG. 3A is a partial section view taken along line 3A--3A of FIG. 3;

FIG. 4 is a bottom and right side isometric view of the section of FIG.3;

FIG. 5 is a side elevation view of the back end of the crane arm of FIG.1;

FIG. 6 is a partial plan view thereof;

FIG. 7 is a section view taken along line 7--7 of FIG. 8;

FIG. 8 is a side elevation view of the front end of the camera crane armof FIG. 1;

FIG. 9 is a partial plan view thereof;

FIG. 10A is a partial schematic illustration of an arm section, as shownin FIGS. 3 and 4;

FIG. 10B is a geometric construction better illustrating the offset andangles of the arm section of FIG. 10A;

FIG. 10C is a geometric construction similar to FIG. 10B and showing analternative embodiment.

FIG. 11 is a partial section view taken along line 11--11 of FIG. 2; and

FIG. 12 is a side elevation view of the supporting frame shown in FIGS.1 and 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now in detail to the drawings, as shown in FIG. 1, the presentcrane arm 20 includes arm sections 22, a counterweight section 24, anose or camera platform section 26, and a central frame section 28,supported on a frame 30. The embodiment shown in FIG. 1 includes two armsections 22 on either side of the frame section 28, with the armsections preferably about 24 inches long. Of course, various numbers ofarm sections 22 may be used, and the lengths of the arm sections may bevaried. Preferably, arm sections are provided in 12 and 24 inch lengths.

FIG. 2 shows the central frame section 28 on the frame 30, without anyarm sections 22. A nose section 26 and a counterweight section 24 may beattached directly to the central frame section 28, to form the shortestembodiment.

As shown in FIGS. 3 and 4, each arm section 22 includes a female end 32and a male end 34. The section ends are preferably flat, so that withthe sections fitted together, the ends fit flush all around. Each armsection 22 includes outer beams 38 joined to a central box section 36,with the arm sections having a substantially I-shaped cross section. Thebox section 36 is preferably hollow, to reduce weight. The arm sectionsmay be manufactured as aluminum weldments. The upper and lower surfaces37 and 39 are preferably flat.

The female end 32 includes threaded holes 42 closest to the upper andlower surfaces 37 and 39. A center hole 48 optionally extends centrallyinto the box section 36, to reduce the weight of the arm section 22 andto allow for cable routing within the arm 20. Pin receiving holes 44 and46 are advantageously located on opposite sides of the center hole 48,as shown in FIG. 3. Referring to FIG. 4, bolts 52 are provided at themale end 34 of the arm sections 22, in alignment with the threaded holes42, when adjacent sections are mated together. Upper and lower pins 54and 56 extend from the flat face of the male end 34, similarly inalignment with the holes 44 and 46. The pins 54 and 56 advantageouslyhave different diameters, so that the arm sections 22 cannot beassembled in a reversed or upside down manner. In the embodiment shown,the upper pin 54 is larger than the lower pin 56, with the upper pinhaving a base diameter of 1 inch and tapering at a 6° included angle toa substantially smaller end diameter, and with the lower pin 56 having abase diameter of 3/4 inch and similarly tapering to a substantiallysmaller end diameter. The pin receiving holes 44 and 46 are also taperedand configured to engage with the pins 54 and 56 as the male end 34 ofone arm section engages a female end 32 of an adjacent section. Becauseof the taper of the pins 54 and 56, no engagement force is needed toassemble adjacent arm sections i.e., the attachment is engagement freeuntil the flat facing surfaces meet.

Referring to FIG. 2A, an undercut 58 is provided to the root diameter ona section of the threads of the bolts 52. Once installed, the bolts 52are captive within the arm sections 22 by set screws 60, (FIG. 3) whichallow the bolts 52 to turn, and slide forward and back, but prevent thebolts 52 from being removed from the arm section.

Referring still to FIG. 3, each arm section 22 includes upper and lowerleveling rods 64 and 65. The ends of the leveling rods at the female endof the arm section 22 have a clevis 70 including a slot 72.Correspondingly, the ends of the leveling rods 64 at the male end 34 ofeach arm section 22 include tabs 74, which mate into the slots 72 (of anadjacent arm section 22). The leveling rods 64 are mounted on bolts 68extending through bushings 71, with the bolts threaded into pivot arms66. The bushings 71, preferably stainless steel, are slightly wider thanthe leveling rods, so that the bolts 68 clamp down on the bushings 71,but not on the leveling rods, which remain free to pivot on the bushings71. The pivot arms are similarly mounted on bolts 67 passing throughbushings 73 slip fit into, and slightly wider than, the box section 36and retained by washer 77 and nut 75, so that the pivot arms 66 canfreely pivot with respect to the box section 36. Referring momentarilyto FIG. 1, quick release pins placed through holes in the clevis 70 andslot 72 at the ends of the leveling rods 64 and 65 allow the levelingrods of adjacent arm sections to be securely attached to each other.Storage holes 78 may be provided through the leveling rods at the femaleends, to conveniently store the quick release pins 76 when not in use.The leveling rods are external on the arm 20, yet are within theenvelope 79 of the cross section of the arm. Accordingly, they areeasily and quickly accessible for assembly and disassembly of the arm,yet they are shielded from damage via dropping, collision, etc.

The lower surface of the upper leveling rod 64, and the upper surface ofthe lower leveling rod 65 include recesses 62, to allow a greater rangeof movement, without interference from the pins 67 or needle bearings71.

Turning to FIGS. 7, 8 and 9, the nose section 26 includes an armature 80having a flat rear surface male end 81 similar to the arm sections 22(but without the outer beams). The armature has a round forward end 82with flat sides and a through bore 91 having a central step 93. AU-plate 85 has inner and outer disk legs 89 and 90, a flat forward plate105, and a shaft section 99. The shaft section 99 extends through thebore and bearings 94 in the bore. An L-plate 84 has a disk leg 98 joinedat a right angle to a forward plate 106. As shown in FIG. 7, the end ofthe shaft section 99 is supported in a counterbore in the disk leg 98. Abolt 86 extends through the L plate 84 and shaft section 99 and threadsinto disk leg 90. Bolts 83 attach the forward plates 105 and 106 to anattaching plate 87. A nose plate 92 is attached to the attaching plate87 via a stud 95 extending from the attaching plate through the verticalleg of the nose plate 92, and a washer 96 and a nut 97 on the stud 95.The front ends of the nose leveling rods 101 and 103 are pivotallyattached via dowels and bearings to the U-shaped plate 85 between thedisk legs 89 and 90.

Dowel pin 107 locates plate 92 every 90 degrees, as the plate 92 isrelocated by revolving around stud 95. The nut 97 is loosened 1/4 inch,then plate 92 is moved out 1/4 inch, allowing dowel 107 to be rotated in90 degree increments around stud 95. The incremental rotation change mayalso of course be set at 45°, 30°, or other angles, as the need mayrequire.

Referring to FIGS. 5 and 6, the counterweight section 24 includes abucket mounting plate 111 having a pyramid-like trapezoidal mounting lug113. A weight bucket or cage 115 advantageously has a chassis 117 forholding counterweights 116, which can be secured by a door 119 hingedonto the chassis 117. A chassis receptacle 112 having a trapezoidal slotis provided on the chassis 117, so that the chassis 117 of the weightbucket 115 can be engaged onto the mounting plate 111. A quick releasepin 114 extends through aligned holes in the mounting lug 113 andchassis 117, to secure the weight bucket 115 onto the arm 20 whileallowing for rapid weight bucket installation and removal. The pyramidlug and slot, each having four angled sides, are self-aligning.Alternative weight bucket designs may also be used. For example, theweight bucket may be split into two smaller spaced apart weight buckets,with a television monitor positioned in between them, along withcontrols for directing a remote camera.

Referring to FIG. 10A, a 24 inch arm section 22 is provided with avertical offset, to help compensate for vertical deflection of the cranearm. Specifically, the female end 32 of the arm section 22 is offsetvertically above the male end 34. In the preferred embodiment, theoffset dimension A is approximately 0.18 inches. The offset is providedby vertically displacing the female end with respect to the male end,such that the box section 36 and the outer beams 38 run slightly uphillfrom the male end 34 to the female end 32. The flat end faces of themale end 34 and the female end 32 are also slightly angled with respectto each other. Specifically, as shown in FIG. 10A, the male end face isvertical, while the female end face is inclined (upwardly) toward themale end face by angle BC, preferably about 0.6 degrees. The bottomsurfaces E and F of the male and female ends are parallel. The threadedbolt holes 42 and pin holes 44 and 46 are (as well as the bolts andpins) preferably perpendicular to surfaces B and C.

FIG. 10B schematically shows an unloaded assembly of the section shownin FIG. 10A, with the offsets and angles greatly exaggerated for clarityof illustration. The two female ends of the frame section 28 arepreferably vertical. The female ends 32 of the two sections 22 adjoiningthe frame section 28 are vertically offset by dimension A, preferablyabout 0.18 inch for the embodiment shown. The faces of the female ends32 are inclined upwardly at an angle BC, preferably about 0.6 degreesfor the embodiment shown. As additional sections 22 are added for alonger arm 20, the offsets A and angles BC accumulate. Without any load,the ends of the beam are slightly above the frame section 28. However,when loaded with a camera on the nose plate 92 and counterweights in theweight bucket 115, the ends of the beam deflect downwardly, so that thearm 20 is substantially straight and the nose plate 92 is substantiallylevel. When loaded under ordinary conditions, surfaces B and C becomesubstantially parallel and angle BC becomes substantially zero, i.e.,the end faces become vertical, as a result of bending deflection of eachsection 22.

In an alternative embodiment shown in FIG. 10C, the angle offset BCgenerally equally on the male and female ends 32 and 34, with each endhaving an end face angle CD of about 0.3 degrees, and with the offset AAreduced to about 0.09 inches. The two female end faces 32 of the framesection 28 may also be similarly angled upwardly, with no offset thenrequired.

Of course, the amount of vertical offset in each arm section 22 requiredto have the crane arm 20 remain straight without sagging when underload, will vary with the length of the arm 20 (i.e., on how many armsections 22 are used), the loads applied, and the moment of inertia ofthe arm 20). Although as arm length increases, the cumulative offsetprovided with each section also increases, arm deflection will vary withthe cube of the length of the arm, whereas the built-in offset of thearm sections accumulates incrementally with length. The maximumpreferred arm length, measured from the center post 160 to the bearings94 in the nose section, is about 26 feet, for best performance. Theapproximate 0.18 inch vertical offset, and approximate 0.6 degreeinclination angle, for the embodiment of FIG. 10A, are selected toprovide a straight beam 20 with a camera payload of about 100-180pounds, with close to the maximum arm length.

Referring to FIGS. 1 and 2, the frame section 28 has two female ends.Accordingly, the male ends 34 of the arm sections 22 are engaged intoboth sides of the frame section 28, so that the built-in offset of thearm 20, on either side of the frame section 28 is in the upwarddirection.

Referring to FIGS. 2 and 11, the frame section 28 includes a box section120, similar to box section 36, but tapering outwardly towards thecenter of the frame section 28. The slash lines 25 in FIG. 2schematically illustrate the position of the leveling rods when the armis titled fully up. Referring specifically to FIG. 11, a tilt axle 130extends through a right cap 136, a right spindle 142, the box section120, a left spindle 152, and is held in place by an axle bolt 156passing through a left cap 154. Inner and outer washers 138 and 140separate the right cap 136 and right spindle 142 from the right upperarm 143 of the U-shaped frame 30. A tilt brake knob 132 is attached tothe tilt axle 130 and spaced apart from the right cap by a thrustbearing 134. The right spindle 142 is attached, preferably welded, tothe box section 120. A spindle bearing 144 and a box section bearing 145pivotally support the frame section 28 on the tilt axle 130. The tiltaxle 130 is fixed on the frame 30. DU bushing 131 allows slidingadjustment when the tilt brake, knob 132 is rotated on the O.D. threadedend of axle 130. The frame section 28 of the arm 20 rotates about axle130.

A disk washer 148 separates the left side of the box section 120 from aleveling rod disk 146. The washers 138, 140 and 148 are preferablyTeflon or Delrin or a similar material. A spacer tube 150 around theaxle 130 maintains spacing between the left spindle 152 and the levelingrod disk 146, so that the leveling rods cannot become clamped betweenthe left spindle 152 and the disk 146, as the arm pivots vertically toraise and lower a camera. Preferably, the leveling rod disk 146, thespacer tube 150, and the left spindle are machined from a single bar,leaving them connected for added rigidity and strength. As shown in FIG.2, clamping bolts 135 are advantageously provided to clamp the left cap154 and spindle 152 to the frame 30.

Upper and lower leveling rod pins 122 extend through the left cap 154and left spindle 152, through holes in the upper and lower leveling rods64 and 65 on the frame section 28, and into the leveling rod disk 48.Thus, the left spindle 152, leveling rods 64 and 65, and leveling roddisk 146 are fixed in position on the left upper arm 141 of the frame30. Bearings may be provided to reduce friction between the pins 122 andthe leveling rods, as they pivot about the pins. The pins 122 fix thecenter of rotation of the leveling rods, causing the ends of theleveling rods to remain vertically aligned, despite vertical pivotingarm movement.

Turning to FIG. 12, a center post 160 is rigidly attached to a cameradolly or crane arm base, such as shown in my U.S. Pat. No. 4,360,187 orU.S. Pat. No. 5,312,121, incorporated herein by reference, so that thearm 20 has a mobile base which can preferably be moved into differentpositions on a floor, track or other surface. A Teflon ring 170 around abase 162 is clamped by a split ring 164. Referring to FIG. 11, a panbrake handle 168 is attached to a pan brake bolt 166 which extendsthrough the split ring 164. As the pan brake handle 168 is turned, thesides of the split ring 164 are pulled together and clamp onto the base162, to stop panning rotation movement.

The frame 30 and base 162 are pivotally supported on the center post 160via upper and lower center bearings 180 and 176. A frame ring 178 andpost cap 182 secure the upper center bearing 180. A post cap bolt 184holds the frame ring 178 and the frame 30 down onto the center post 160.

In use, the frame 30 carrying the frame section 28, as shown in FIG. 2,is bolted onto a center post 160 of a dolly or mobile base via the postcap bolt 184. Alternatively, if the frame 30 is provided with a centerpost 160, as shown in FIGS. 2 and 12, then the center post 160 issecurely attached to the dolly or mobile base. The appropriate number ofarms sections 22 are then fitted together on either side of the frame30, to achieve the desired arm length. Specifically, the pins 54 and 56are aligned with and moved into the holes 44 and 46, with adjoiningsections moved together until the flat ends touch. The bolts 52 are thenturned in to hold adjoining sections together. Due to the flat endsurfaces, matching pin and hole contours, and precise machining, eventightening the bolts 52 by hand provides for a rigid arm 20. However,tightening the bolts 52 with a wrench prevents the bolts from becominginadvertently loosened. As the frame sections are brought together, theholes in the leveling arm clevis 70 and tab 74 align with each other.Locking pins 114 are inserted through the holes, to securely link theupper and lower leveling rods 64 and 65 of adjoining arm sections 22, asshown in FIG. 1. The attachment of arm sections 22 to the frame section28 is achieved in a similar way, except that the frame section 28 hastwo female ends. The weight bucket and nose section are attached atopposite ends, in a similar manner. Weights are placed into the weightbucket to balance the arm.

In a preferred embodiment, with the arm sections having a height ofabout 8.2 inches, a width of about 6 inches, a box section wallthickness of about 1/4 of an inch, and a moment of inertia I of about 44inches⁴, each 24 inch arm section weighs about 22 pounds. The arm 20 cantherefore be readily assembled by attaching the arm sections to theframe section supported on a dolly or mobile base. Alternatively,multiple sections can first be attached together and then attached tothe frame section 28, although this requires the lifting of greaterweight. The outer beams 38 serve as handles for lifting and maneuveringindividual arm sections 28, as well as maneuvering the entire arm 20during filming.

The leveling system is next to the box section and in between the leftside outer beams. In this position, the leveling system (i.e., theleveling rods and their supports and attachments) is shielded fromdamage and abuse (e.g., dropping arm sections), allows for a morecompact design, and is out of the way during use. In addition, as theleveling system is well inside of the envelope 79, the outer beams maybe grasped and used as handles away from any potential pinch points.

To lock the arm 20 against vertical movement (i.e., pivoting movementabout the tilt axle 130, the tilt brake knob 132 is turned, causing thetilt axle 130 to act as a draw bar and being secured by the axle bolt156. Correspondingly, the upper arms 141 and 143 of the frame 130 aremoved slightly towards each other, clamping the right spindle 142against the inner Teflon washer 140 and the upper arm 143, and at thesame clamping the left side of the box section 120 against the diskwasher 148 and the leveling rod disk 146, to the point where frictionsmoothly resists pivoting movement. When the tilt brake knob 132 isbacked off, the clamping force on the frame section 28 is released andthe low friction washers 138, 140, and 148 allow the beam 20 to freelypivot vertically. To prevent panning motion, the pan brake handle 168 issimilarly tightened, drawing the split ring 164 together and clamping iton the base 162.

Thus, a novel camera crane arm and camera crane arm section having beenshown and described. Many changes and modifications can of course bemade without departing from the spirit and scope of the invention. Theinvention, therefore, should not be restricted, except by the followingclaims.

I claim:
 1. A camera crane arm comprising:a frame section having a firstend and a second end; a first arm section attached to the first end anda second arm section attached to the second end; the first and secondarm sections extending upwardly from the frame section at an inclinationangle; a third arm section attached to the first arm section and afourth arm section attached to the second arm section; a third andfourth arm sections extending upwardly at an inclination angle from thefirst and second arm sections; respectively; and the third and fourtharm sections positioned entirely above the first and second arm sectionsrespectively, when the crane arm is unloaded, and the arm sectionsbending downwardly when the crane arm is loaded, such that the armsections are generally parallel to each other and the crane arm isgenerally straight, when loaded.
 2. A camera crane arm sectioncomprising:a beam section having a first end and a second end; a fistend face on the first end and a second end face on the second end, andwith the second end face oriented at an inclination angle with respectto the beam section, so that attaching the second end face to a verticalsurface causes the beam section to extend away from the vertical surfaceat the inclination angle; first end fastener elements on the endcomprising bolts or pins; and second end fastener elements on the secondend comprising receiving holes or threaded holes.
 3. The camera cranearm section of claim 2 wherein the inclination angle is about 0.6degrees.
 4. The camera crane arm section of claim 2 further comprising aplurality of outer beam sections joined to the beam section.